The present invention relates to a depth gauge comprising an elongate support which is intended to be in an upright orientation when in use, N sets of emitters, where N is an integer greater than 1, each set of emitters being mounted on the elongate support and being spaced apart therealong, and N sets of detectors, each set of detectors being mounted on the elongate support and being spaced apart therealong, the 2N sets being directed in different respective directions and the emitters and the detectors being electrically connected to a processor to enable the latter to send signals to the emitters and receive signals from the detectors.
One such gauge is described and illustrated inUS 2011/219868 A1, for measuring the depth of snow.